06:53Newton's 2nd Law (1 of 21) Calculate Acceleration w/o Friction, Net Force HorizontalStep by Step Science391views
Multiple ChoiceAn 800-kg car is traveling along a horizontal road directly towards a cliff. The driver notices and brakes, resulting in a 5,000-N net force slowing the car down. If the car's initial speed was 20 m/s and the car stops just before going over the cliff, how far away was the car from the cliff when the driver hit the brakes?1418views32rank4comments
Multiple ChoiceThe following forces are acting on a 250g box on a horizontal surface. A downward force of gravity with magnitude 2.45N. An upward normal force with magnitude 2.45N. A rightward pull from a rope of 5.0N. A leftward kinetic friction force with magnitude 7.5N. At this instant, what is the magnitude of the acceleration of the box?423views1rank1comments
Multiple ChoiceTabletop shuffleboard is a popular pub game where players slide pucks across a tabletop trying to get them as close to the end of the table as possible, without falling off. Shuffleboard tables are typically covered in shuffleboard wax, which gives a very low coefficient of kinetic friction between the table and puck. Suppose that one particular table is 6.0 long m and has a coefficient of kinetic friction of 0.080. What speed should a player give to a puck on one end of the table so the puck just makes it to the far end?545views1comments
Textbook Question(II) A child on a sled reaches the bottom of a hill with a velocity of 10.0 m/s and travels 25.0 m along a horizontal straightaway to a stop. If the child and sled together have a mass of 60.0 kg, what is the average retarding force on the sled on the horizontal straightaway?272views
Textbook QuestionWhen jumping straight up from a crouched position, an average person can reach a maximum height of about 60 cm. During the jump, the person's body from the knees up typically rises a distance of around 50 cm. To keep the calculations simple and yet get a reasonable result, assume that the entire body rises this much during the jump. (a) With what initial speed does the person leave the ground to reach a height of 60 cm?254views
Textbook QuestionFIGURE EX6.10 shows the force acting on a 2.0 kg object as it moves along the x-axis. The object is at rest at the origin at t = 0s. What are its acceleration and velocity at t = 6 s?862views2rank
Textbook QuestionThe forces in FIGURE EX6.9 act on a 2.0 kg object. What are the values of ax and ay, the x- and y-components of the object's acceleration? 1269views
Textbook QuestionCompressed air is used to fire a 50 g ball vertically upward from a 1.0-m-tall tube. The air exerts an upward force of 2.0 N on the ball as long as it is in the tube. How high does the ball go above the top of the tube? Neglect air resistance.552views
Textbook QuestionA 20,000 kg rocket has a rocket motor that generates 3.0 x 10^5 N of thrust. Assume no air resistance. (a) What is the rocket's initial upward acceleration?461views1rank
Textbook QuestionA horizontal rope is tied to a 50 kg box on frictionless ice. What is the tension in the rope if: (b) The box moves at a steady 5.0 m/s?669views
Textbook Questiona. A rocket of mass m is launched straight up with thrust Fₜₕᵣᵤₛₜ. Find an expression for the rocket's speed at height h if air resistance is neglected.329views
Textbook QuestionYour forehead can withstand a force of about 6.0 kN before fracturing, while your cheekbone can withstand only about 1.3 kN. Suppose a 140 g baseball traveling at 30 m/s strikes your head and stops in 1.5 ms. a.What is the magnitude of the force that stops the baseball?1165views
Textbook QuestionA 500 g model rocket is on a cart that is rolling to the right at a speed of . The rocket engine, when it is fired, exerts an 8.0 N vertical thrust on the rocket. Your goal is to have the rocket pass through a small horizontal hoop that is 20 m above the ground. At what horizontal distance left of the hoop should you launch?823views
Textbook QuestionAs a science fair project, you want to launch an 800 g model rocket straight up and hit a horizontally moving target as it passes 30 m above the launch point. The rocket engine provides a constant thrust of 15.0 N. The target is approaching at a speed of 15 m/s. At what horizontal distance between the target and the rocket should you launch?428views
Textbook QuestionTwo rock climbers, Paul and Jeanne, use safety ropes of similar length. Jeanne's rope is more elastic, called a dynamic rope by climbers. Paul has a static rope, not recommended for safety reasons.<IMAGE>(a) Jeanne (Fig. 4–72) falls freely about 2.0 m and then the rope stops her over a distance of 1.0 m. Estimate how large a force (assume constant) she will feel from the rope. (Express the result in multiples of her weight.)182views
Textbook QuestionA 25-g projectile is fired into a cube of ballistic gel at a velocity of 360 m/s. If the projectile penetrates 15 cm into the gel before stopping, find the average force exerted by the gel onto the projectile. Use (a) kinematics and dynamics (Newton's laws) 265views
Textbook Question(III) A particle of mass m, initially at rest at x = 0, is accelerated by a force that increases in time as F=Ct² . Determine its velocity v and position x as a function of time.339views
Textbook Question(II) At the instant a race began, a 65-kg sprinter exerted a force of 720 N on the starting block at a 22° angle with respect to the ground.(a) What was the horizontal acceleration of the sprinter?235views
Textbook Question(II) At the instant a race began, a 65-kg sprinter exerted a force of 720 N on the starting block at a 22° angle with respect to the ground.(b) If the force was exerted for 0.32 s, with what speed did the sprinter leave the starting block?231views
Textbook QuestionTwo rock climbers, Paul and Jeanne, use safety ropes of similar length. Jeanne's rope is more elastic, called a dynamic rope by climbers. Paul has a static rope, not recommended for safety reasons.<IMAGE>(b) In a similar fall, Paul's rope stretches by only 30 cm. How many times his weight will the rope pull on him? Which climber is more likely to be hurt?179views
Textbook QuestionYou are driving home in your 860-kg car at 15 m/s. At a point 45 m from the beginning of an intersection, you see a green traffic light change to yellow, which you expect will last 4.0 s, and the distance to the far side of the intersection is 65 m (Fig. 4–71). <IMAGE>(a) If you choose to accelerate, your car's engine will furnish a forward force of 1200 N. Will you make it completely through the intersection before the light turns red?206views
Textbook QuestionSuppose a 65-kg person jumps from a height of 3.0 m down to the ground.(c) Estimate the decelerating force if the person lands stiff-legged so d ≈ 1.0 cm .<IMAGE>204views
Textbook Question(II) The drag force on large objects such as cars, planes, and sky divers moving through air is more nearly F_D = -cv² .(a) For this quadratic dependence on v, determine a formula for the terminal velocity vτ , of a vertically falling object..222views
Textbook Question(III) An object moving vertically has v→ =v₀ → at t = 0 . Determine a formula for its velocity as a function of time assuming a resistive force F = -bv as well as gravity for two cases:(b) v₀→ is upward.88views
Textbook Question(III) Air resistance acting on a falling body can be taken into account by the approximate relation for the acceleration: a = dv/dt = g ― kv , where k is a constant. (b) Determine an expression for the terminal velocity, which is the maximum value the velocity reaches.221views
Textbook Question(II) A 2.0-kg purse is dropped from the top of the Leaning Tower of Pisa and falls 55 m before reaching the ground with a speed of 27m/s . What was the average force of air resistance?220views
Textbook Question(II) The terminal velocity of a 3 x 10⁻⁵ kg raindrop is about 9 m/s. Assuming a drag force FD = -bv , determine (b) the time required for such a drop, starting from rest, to reach 63% of terminal velocity.220views
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